AIM: Bacteriological and electron microscopic study of skin of healthy persons and patients with atopic dermatitis (AD). MATERIALS AND METHODS: Fifteen patients (7 males and 8 females aged 17-53 years) with lichenoid form of AD treated in dermatovenerologic outpatient clinics were compared with group of virtually healthy 10 persons of the same age. Comparative study of skin and electron microscopic evaluation of ultrathin sections from affected areas of the skin were performed in all participants. Main representatives of resident and facultative groups of microbiota were counted. RESULTS: Differences in microbial spectrum and level of physiological activity of microorganisms colonizing skin surface of healthy persons and patients with AD were revealed. Unlike microbes on healhy skin, the microorganisms colonizing skin of the patients with AD were characterized by profound polymorphism of cells. Widening of population spectrum of opportunistic microorganisms belonging to genuses Staphylococcus, Corynebacterium, and Candida was accompanied by manifestation of destructive changes of the skin of patients with AD. Electron microscopic evaluation of skin of patients with AD showed that bacterial cells located predominantly in upper layers of epidermis. Major number of microorganisms colonized corneal layer and located between friable skin squama. CONCLUSION: Changes of skin microbiota with marked pathomorphologic changes of keratinocytes were observed in patients with AD that necessary to consider during basic therapy of this disease.